Z 40/2.0: strange backlight effect - Printable Version
+- Opticallimits (https://forum.opticallimits.com)
+-- Forum: Forums (https://forum.opticallimits.com/forumdisplay.php?fid=4)
+--- Forum: Nikon (https://forum.opticallimits.com/forumdisplay.php?fid=12)
+--- Thread: Z 40/2.0: strange backlight effect (/showthread.php?tid=5168)
Z 40/2.0: strange backlight effect - mst - 10-24-2021
It seems if the sun (or strong artifical light) hits the lens from just outside the image field at a particular angle, something in the lens creates this slight shadow on the image side. Works only on the short sides (but on both of them). My assumption is that it's the effect of a reflection from the rectangular mask covering the rear element of the lens.
Simulated backlight with the iPhone LED light:
Same with the sun as light source:
Also works with 'actual' backlight subjects:
The shadow shows up only at a particular angle, as mentioned. So, in practice it's probably not really a big issue, since it's difficult to hit that angle exactly and not too difficult to move a little bit to get rid of the shadow. Still, a reproducible issue of the lens.
RE: Z 40/2.0: strange backlight effect - Brightcolours - 10-24-2021
"... that it's the effect of a reflection from the rectangular mask covering the rear element of the lens."
I can understand that you think the mask causes the "line". But I do not understand the "reflection from the rectangular mask" part.
The light enters the lens at one end, and gets recorded on the other side by the image sensor. Somewhere before all the light gets recorded by the sensor, the mask blocks part of it. What do you think actually is going on? I do not see a mask "reflection", more a mask-mask effect. My brain does not yet compute what is going on.
Does the flare just get masked? Is it that simple?
RE: Z 40/2.0: strange backlight effect - photonius - 10-24-2021
Indeed strange. Looks like the light is indeed hitting some mask somewhere, and diffracting along the sharp edge (at least in the first image). Not sure if that explains the last backlight image.
Maybe you manipulate that mask? (post-it, some black felt stuck on, ...) And see if it affects the image. Then you would know if it is the mask.